Foam inhibition in hydrocarbon oils



States 2,862,885 FOAM rwrnBrrioN IN HYDROCARBON orrs' Rudolph S. Nelson, Larchmont, and Charles W. West,

Kenmore, N. Y., assignors to Union Carbide Corporation, a corporation of New York No Drawing. Application January 18, 1955 Serial No. 482,657

11 Claims. (Cl. 25249.6)

This invention relates to the prevention of excessive foaming of petroleum-type oils, especially those in the lubricating oil viscosity range. In particular it relates to petroleum-type products which have been rendered nonfoaming by the addition of minute amounts of polymers of vinylalkoxysilanes or vinylalkylalkoxysilanes.

It is the principal object of this invention to suppress foaming in petroleum-type oils and particularly mineral v.oils in the lubricating oil viscosity range. A further object is to provide the art with novel anti-foam additives of exceptional effectiveness. These and additional objects and advantages of the present invention will be apparent from the following detailed description.

Various members of the family of organic compounds referred to generically as silicones or polysiloxanes have been found useful as foam depressors or preventives.

.Silicones, generally speaking, have a chemical structure .of the type:

wherein the R groups are either hydrogen or hydrocarbon radicals and x is a positive integer. While the silicones generally possess thermal stability far in excess of hydrocarbons they lack much of the lubricating properties of oils derived directly from petroleum or synthetic polymers of the petroleum type. On the other hand, although a minute amount of certain silicones will suppress foaming of various petroleum stocks, hydrocarbons have no such ability. For these as well as other reasons it may' novel polyvinylalkoxysilanes and polyvinylalkylalkoxy silanes described and claimed in the copending application of Bailey and Mixer for Letters Patent, Serial No. 374,137, filed August 13, 1953, now U. S. Patent No. 2,777,869, have been found to have exceptional foam inhibiting properties. These homopolymers and the method' of preparation are also described in an article by Wagner et al. in Industrial and Engineering Chemistry 45, 367-373 195 3).

One of the most vexing foaming problems encountered with petroleum and its products is the foaming of lubricating oils in engines, turbines, etc. On the other hand the foaming of petroleum-type oils generally when poured into a tank car or even a smaller container is a source of considerable concern. Foaming of a lubricating oil results in an inadequate lubricating film over the moving parts and a consequent reduction in effectiveness of the oil.

foaming of oil products during filling of shipping con- 2,862,885 Patented Dec. 2, 1958 tainers of various sizes results either in waste of valuable container capacity or loss of an excessive amount of time waiting for the foam to subside. The two foaming prob- I vinylalkoxysilanes, which may be polymerized through the vinyl groups to produce so-called homopolymers, in

the presence of a peroxide may be represented by the formula:

(R)eSi(OR where R is a monovalent hydrocarbon radical, R is an alkyl radical including alkoxyalkyl, x is 0, 1 or 2, and y is 1, 2 or 3, the sum of x and y being 3. These compounds may be employed in the production of the novel foam inhibitors of the present invention. As indicated above, the polymerization of such silanes by the process described in copending Serial No. 374,137 takes place at the vinyl groups and results in homopolymers of the general structure:

where n is a positive integer greater than one and R, R x and y are as above defined. It will be understood that the term vinylalkoxysilanes as employed herein refers to compounds containing at least one alkoxy radical attached to the pendant silicon atom and will therefore include vinylalkylalkoxysilanes.

It isimportant to recognize that the homopolymers of the type herein described differ from other vinyl siloxane polymers in that polymerization occurs through the vinyl group to produce basic carbon to carbon chains, rather than through the silicon and oxygen atoms to yield the alternate silicon-oxygen type chain. As a result the homopolymers contain at least one long hydrocarbon chain, which contributes to substantially greater compatability with organic liquids such as petroleum oils and the like.

Although the method whereby the above-described homopolymers are produced is not part of the present invention inasmuch as that subject matter is described and claimed in the aforementioned copending application, it is important to prepare these homopolymers carefullyand in accordance with the method of the aforementioned application. The polymerization of vinylalkoxysilanes has been suggested in the prior art by other methods but these result only in residue polymers which are brittle resins of a brown to black color and the method prescribed for use in accordance herewith results in true homopolymers which are colorless to light colored products and range from viscous liquids to gummy or plastic solids. In this connection it should be noted that the polymerization of vinylalkoxysilanes to such desirable products requires the use of highly pure monomers and a very specific catalyst, viz., di-t-butyl peroxide, which is markedly effective in the production of viscous polymers.

The polymerization process required to prepare the homopolymers useful in accordance herewith is a conventional vinyl-type polymerization employing the specified catalyst, di-t-butyl peroxide with heating until polymerization occurs. In addition, however, to the requirement for a specific catalyst and the necessity of employing the pure monomer it is preferred that the polymerization be conducted in an inert, substantially anhydrous atmosphere. The presence of oxygen, air or substantial amounts of moisture is undesirable, as polymer viscosity is reduced thereby. However, some degree of polymerization will occur even under these adverse conditions but it is certainly more desirable and preferred for use in accordance herewith that an inert atmosphere such as nitrogen, argon, carbon dioxide or other inert gas be maintained over the reaction mixture during polymerization.

The concentration of the catalyst and the temperature of polymerization also have an eifect on polymer prop erties. And in general it may be said that polymer viscosity will increase as catalyst concentration is increased until an optimum concentration is reached. At low catalyst concentrations the polymer viscosity increases with increasing polymerization temperature but at higher catalyst concentrations the polymer viscosity appears to decrease with increasing polymerization temperature. These effects are shown in the following table:

TABLE I.EFFECT OF TEMPERATURE AND CATALYST 31450 IIIIIIIIII IIIIIIIII 239 239 302 Reaction time ..hr. 16 64 10 1 This product was stripped of 3 wt. percent lights after which it was too viscous for the test.

The range of molecular weight of the herein described polymers within which the anti-foam properties are exhibited to the greatest extent is from about 325 to about 8,000 and preferably from about 3,000 to about 8,000. Polymers having a molecular weight higher than about 8,000 may, of course be employed. When higher molecular weight polymers are employed, for example in the upper range recited, it has been found that a somewhat smaller amount of the polymer is required to obtain desirable foam suppression. Thus, in the range of from about 3,000 to about 8,000 molecular weight, the quantity of polymer employed may vary from as little as 2 parts per million (p. p. m.) to a considerably larger amount, the upper limit ordinarily being determined by economic considerations. In the molecular weight range below about 3,000 it is preferred to employ at least about 50 p. p. m. of a polymer and more if economics permit.

ethoxsilane, vinylethyldiethoxysilane, vinylmethyldiethoxysilane, etc. Thus, in the general formulawherein R represents a monovalent hydrocarbon radical, e.. g. alkyl, cycloalkyl, aryl, alkylaryl or aralkyl containing from 1 to about 18 carbon atoms and preferably from 2 to about 8 carbon atoms, and R may be an alkyl radical containing from 2 to about 18 carbon atoms and preferably from 2 to about 8.

The method employed to evaluate the effectiveness of the compounds of the present invention in the suppression of foam is outlined below. It is essentially the ASTM test D-892-46T. In this test the test sample at room temperature (ca. 80 F.) was poured into a 1,000 ml. cylinder until the liquid level was at the 190 ml. mark. The air inlet tube with an attached diffuser stone was then inserted into the oil and after five minutes the air was turned on at the rate of about 95 ml. per minute. The air was introduced for five minutes and at the end of that time it was turned off and the level to which the foam above the liquid had risen in the cylinder was immediately recorded. The foam was then allowed to stand for an additional ten minutes and the volume of foam again recorded. If the foam collapsed entirely within ten minutes, nil foam would be noted. Following this a second sample of the oil being tested was placed in a clean 1,000 ml. cylinder and the test was repeated as before, with the exception that a temperature of 200 F. (obtained by means of a constant temperature bath) instead of room temperature was employed.

The so-called reference oil or control referred to in the following Table H was prepared by adding 0.3% of lecithin to petroleum oils free of additives. The lecithin, of course, promotes foaming. The various anti-foam additives tested, the results of which are reflected in the following table, were added to the reference oil as a 1% (grams per volume) solution in toluene or kerosene. And the anti-foam concentrate was added dropwise to the mechanically stirred oil at about 140 F. with the stirring being continued for approximately ten minutes after addition of the foam-suppressing additive. Results of a series of tests based upon the above procedure in which reference oils containing an additive of the present invention are compared with the reference oil free of any foamsuppressor and the reference oil containing varying amounts of a well known silicone type foam suppressor, viz., dimethyl silicone.

TABLE II Foam volume at room Foam volume at temp. 200 F. Conc., Antifoam composition p. p. 111.

After After 10 min. After After 10 min. 5 min. settling 1 5 min. settling I bubbling bubbling Reference oil alone (Sinclair Opallne gear oil 1,000 SUS at 100 F.

base plus 0.3% lecithin) I 570 530 565 0 (6 min. Ref. plus dimethyl silicone, 350 cs 10 90 30 410 0 (3 min. Do 10 0 (3 min.) 230 0 (2 min. Ref. plus dimethyl silicone, 1,000 cs 10 0 0 10 0 1 min. Ref. plus dimethyl silicone, 10,000 cs 10 0 0 10 0 1 min. Ref. plus polyvlnyl-triethoxysilane (325 M. W.) 10 530 480 430 0 (5 min.) Do 50 10 0 (2 mln.; 0 0 Ref. plus polyvinyl-triethoxysilane (5,000 M. W.) 10 10 0 0 0 -g Ref. plus polyviuyl-triethoxysilane (5,700 M. W.) 10 0 0 10 0 1 min. Ref. plus polyvinyl-triethoxysilane (7,820 M. W.) 10 10 0 1 min.) 10 0 1 miIL;

Do 5 10 0 (3 min.) 20 0 1 min.

1 Times given parenthetically pertain to complete collapse of foam. 2 Gliddol R, commercial product of Glidden Corporation.

Typical of the vinylalkoxysilanes which may be employed to produce polymers suitable for foam suppression in accordance herewith are vinyltriethoxysilane, vinyltributoxysilane, vinylbutyldiethoxysilane, vinyldibutylethoxysilane, vinylhexyldibutoxysilane, vinyldecyldipentoxysilane, vinylphenyldiethoxysilane, vinyldiphenyl Synthesis of homopolymers of the type described above is exemplified by the following examples which, of course, are set forth for purposes of explanation and illustration and not of limitation. It will be noted in this connection, that Example 2 is concerned with the preparation of a number of difierent vinyl ethoxysilanes.

Example 1 Di-t -b'utyl peroxide (0.50 gram) was diluted to25.0 ml. with purified vinyltriethoxsilane in a Norm'ax volumetric flask to form a catalyst solution. Then 215ml. of purified vinylthiethoxsilane (B. P. 158 F. at 30 mm. Hg; 11 1.3966, (1 4 0.9036; MR calculated 50.61; observed, 56.66; infrared spectrum No. 61-9, efilux time unheated 16.4 seconds in tube A) and 1.00 inlf'jof the catalyst solution were placed in a rigorously cleaned, 25 mm. x 200 mm. Pyrex test tube flushed with argon and equipped with a well-fitting cork. Thus the contents of the tube were 22.5 ml. (20.0 grams) of vinyltriethoxysilane and 0.02 gram (or 0.10 weight percent of di-t-butyl peroxide. The contents were shaken and then the space above the contents again flushed with argon. The contents and test tube were heated in a constant temperature oil bath at 239 F. for 16 hours. The polymerized material was stripped of monomer by heating at 239 F. for 16 hours. The polymerized material was stripped of monomer by heating at 239 F. and 1 mm. Hg absolute pressure until nor more monomer was removed (about 1 hour). Approximately 0.5 gram of monomer was removed indicating a 97% conversion. The resulting product was a clear, colorless, very viscous liquid having the following physical properties: n =1.4445 d 4=0.97 to 1.00 Infrared spectrum No. 621 Efliux time in tube C 570 seconds Effiux time extrapolated to tube A 65,000 seconds The product was examined by infrared absorption and the several absorption bands accepted as signifying the presence of the vinyl (C=C) double bond were shown to be missing. This proves that the vinyl group has reacted.

INFRARED ANALYSIS Bands Probable Assignment Monomer Polymer 3. 27 u. Missing" 'O-'H stretch in vinyl group. 6. 22 do C=C stretch in vinyl group.- 7. 09 Reduced. CH2 deformation in vinyl group (sym.

in-plane). 7. 83 [L- Missing CH1 deformation in vinyl group (inp an 9.88 1. do CH1 deformation in vinyl group (out-oip ane 10.38 p. OH deformation in vinyl group (out-ofplane) plus Si-O-C vibration. 10. 45 n Si-O-G vibration (less intense than combined band at 10.38 in monomer).

Example 2 The homopolymerization of the vinylalkoxysilanes also occurs when a monovalent hydracarbon radical, such as an aryl or alkyl radical, replaces one or two of the alkoxy groups. Thus vinylethyldiethoxysilane, vinylphenyldiethoxysilane and vinyldiphenylethoxysilane were polymerized under conditions tabulated below by heating for 16 hours at 239 F.

TABLE III.-HOMOPOLYMERIZATION OF OTHER VINYLETHOXYSILANES Product efilux Time in seconds Expt. Di-t-butyl peroxide conc.

No. Monomer 0.02 0.10 0.5

None weight weight weight percent percent percent (a) Vinyltriethoxysilane 19.4 136 36,000 66,000 Vinylethyldiethoxysilane. 17.2 18.8 25 6,000 (c) Vinylphcnyldicthoxysi- 19.3 23.2 33.1 134,000

ne. (d) vilnyldiphenylethoxysi- 23.2 27.7 36.0 8,870

ane.

1 Efliux time measured in Tube A. 2 Extrapolated values from times measured in Tube 0.

The physical properties of the vinyldiphe'nylethoxysilane monomer were: B. P. 298 F. at 5.0 mm. Hg; 11 1.5504; (1254 1.0169; MR observed, 79.73, calculated 79.47. When samples of vinyldiphenylethoxysilane con-- taining 1% di-t-butyl peroxide were heated for 16 hours at 239 F., the product was a plastic solid; when heated for 16 hours at 302 F., the product was a brittle solid; and when heated for 144 hours at 212 F., the product Was a viscous liquid having an efllux time in tube A 18,200 seconds.

Although the description hereinabove set forth of the type of monomer which may be employed to produce foam-suppressing polymers falling within the scope of the present invention has been limited to vinyl derivatives, it should be understood that homopolymers or copolymers of alkenylalkoxysilanes generally may be employed in accordance herewith. Thus polymers of allylalkoxysilanes and cyclohexenylalkoxysilanes may also be employed.

It should be understood further that the foam-suppressing additives herein described may be employed in petroleum oils generally and in lubricating oils particularly which contain additional additives. Thus, for example, lubricating oils generally contain one or more of the following types of additives, viz., extreme pressure additives, viscosity indexed improvers, oiliness agents, detergents, etc. It is in connection with detergents particularly that foam-suppressing additives of the type described will find particular utility inasmuch as oils containing the same have a greater tendency toward foaming. In this connection one of the best known and most Widely used types of petroleum detergents are the phosphorus and sulphur-containing materials prepared by reaching the phosphorous sulphide with a hydrocarbon such as a butylene polymer and then neutralizing the same with sodium potassium hydroxide orthe like. Other detergent type additives commonly employed in lubricating oils are the alkaline earth petroleum sulfonates, the alkaline earth phenyl stearates, the alkaline earth alkyl phenol sulphides, etc. The anti-foam agents of the present invention may, of Course, be employed in lubricating oils containing detergent materials such as these as well as various other detergent additives not herein enumerated.

It should be further understood that the invention is not limited to the prevention of foaming of petroleum oils. Thus, oils of the petroleum type which are commonly employed as substitutes for petroleum oils, particularly in lubricating or hydraulic applications, may be inhibited against foaming by the use of the polymers herein described. These include polymeric hydocarbons resulting from the polymerization of various unsaturated hydrocarbons, e. g. polybutenes, polypropylene mixtures of these, etc. oleaginous materials of the polyalkylene oxide type (polyalkylene glycols, esters thereof, etc.) e. g., the so-called Ucon oils marketed by Carbide & Carbon Corporation; aliphatic diesters of dicarboxylic acids such as the butyl, hexyl, Z-ethyl-hexyl, decyl, lauryl, etc. esters of such acids as sebacic acids, adipic acids, azelaic acids, etc. Accordingly, the term petroleum-type oil as employed in the appended claims shall be understood to include not only the hydrocarbon oils derived directly from petroleum but other organic liquids having a basic carbon-hydrogen structure and having many of the properties of petroleum hydrocarbons such as those above enumerated.

Moreover, the term oil as employed herein and in the claims is used in its broadest sense. Thus, nonoleaginous materials such as gasoline, kerosene and similar materials, to the extent that such materials may be improved in their foaming characteristics by the addition thereto of the polymers herein described, are included within the meaning of the term oil as employed in the claims.

Having thus described our invention, what we claim as novel and desire to protect by Letters Patent is set forth in the following claims: 1

1. A hydrocarbon oil containing a minor amount sufiicient to inhibit foam' of a homopolymer of a monovinylalkoxysilane having a molecular weight of at least about 325 which had been polymerized through the vinyl group.

2. A hydrocarbon oil containing from about 2 parts per million to about 50 parts per million of a homopolymer of a monovinylalkoxysilane which had been polymerized through the vinyl group to a material of from about 325 to about 8000 molecular weight.

3. A hydrocarbon oil containing from about 2 parts per million to about 50 parts per million of a homopolymer of a monovinylalkoxysilane which had been polymerized through the vinyl group to a material of from about 3000 to about 8000 molecular weight.

4. A mineral lubricating oil containing from about 2 parts per million to about 50 parts per million of homopolymer of a monovinylalkoxysilane which had been polymerized through the vinyl group to a material having a molecular weight from about 3000 to about 8000.

5. A petroleum hydrocarbon fraction containing a minor amount sufficient to inhibit foam of homopolymer of a monovinylalkoxysilane which had been polymerized through the vinyl group to a material having a molecular weight of from about 325 to about 8000, said monovinyl-alkoxysilane having the general formula:

(R),-Si(OR wherein R is a monovalent hydrocarbon radical, R is an alkyl radical, x is selected from the group consisting of 0, 1 and 2, y is a positive integer from 1 to 3, both inclusive, and x+y=3.

6. A petroleum hydrocarbon fraction containing a minor amount sufiicient to inhibit foam of homopolymer of monovinylalkoxysilane which had been polymerized through the vinyl group to a material having a molecular weight of from about 325 to about 8000, said monovinylalkoxysilane having the general formula:

orrr=cn (R)=-S i(OR wherein R is a monovalent hydrocarbon radical containing from 1 to about 18 carbon atoms, R is an alkyl radical containing from 1 to about 18 carbon atoms x is selected from the group consisting of 0, 1 and 2, y is a positive integer from 1 to 3, both inclusive, and x+y=3. 7. The method of suppressing foaming of hydrocarbon oils which comprises admixing with said oil a minor amount sufiicient to inhibit foam of a homopolymer of monovinylalkoxysilane which had been polymerized in the presence of di-t-butyl peroxide through the vinyl group to a clear light colored product.

8. The method of claim 7 wherein the amount of homopolymer admixed with said hydrocarbon oil is from about 2 parts per million to about 50 parts per million.

9. The method of claim 7 wherein the homopolymer admixed with said hydrocarbon oil is prepared from vinyltriethoxysilane.

10. The method of suppressing foaming of a hydrocarbon oil which comprises admixing with said hydrocarbon oil a minor amount of a homopolymer of a vinylalkoxysilane having a molecular weight of at least about 325 which homopolymers were prepared by heating a vinylalkoxysilane of the structure- CHFCH R)u where R is a monovalent hydrocarbon radical, R is an alkyl radical, x is selected from the group consisting of 0, 1 and 2, y is a positive integer from 1 to 3, both inclusive, and x+y=3, in the presence of di-t-butyl peroxide.

11. A mineral lubricating oil containing from about 2 parts per million to about 50 parts per million of homopolymer of a monovinylalkoxysilane which had been polymerized through the vinyl group to a material having a molecular weight from about 325 to about 8000.

OTHER REFERENCES Wagner et al.: Ind. and Eng. Chem, vol. 45, 1953, pp. 367-373.

UNITED STATES PATENT OFFICE Certificate of Correction Patent No. 2,862,885 December 2, 1958 Rudolph S. Nelson et a1.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5, line 5, for "vinylthiethoxsilane read vinyltriethoxysilane; line 7, for 56.68 read 50.66; lines 17 to 19, strike out The polymerized material was stripped of monomer by heating at 239 F. for 16 hours; line 21, for nor read -no-; column 6, line 34:, for reaching read -reacting; line 36, for sodium potassium hydroxide read -sodium or potassium hydroxide.

Signed and sealed this 28th day of April 1959.

[SEAL] Attest T. B. MORROW, ROBERT C. WATSON,

Attestz'ng 0772067. Commissioner of Patents. 

1. A HYDROCARBON OIL CONTAINING A MINOR AMOUNT SUFFICIENT TO INHIBIT FORM OF A HOMOPOLYMER OF A MONOVINYLALKOXYSILANE HAVING A MOLECULAR WEIGHT OF AT LEAST ABOUT 325 WHICH HAD BEEN POLYMERIZED THROUGH THE VINYL GROUP. 